General Anatomy of the Abdomen Part 2 PDF

15/02/24 General anatomy of the abdomen I: part 2 Learning objective: describe the anatomy of the GI tract above the diaphragm – mouth, tongue, pharynx and oesophagus. The GI tract: The GI tract extends from the mouth to the anus. Mouth: Inferior to nasal cavities. Roof: hard palate and soft palate....

15/02/24 General anatomy of the abdomen I: part 2 Learning objective: describe the anatomy of the GI tract above the diaphragm – mouth, tongue, pharynx and oesophagus. The GI tract: The GI tract extends from the mouth to the anus. Mouth: Inferior to nasal cavities. Roof: hard palate and soft palate. Floor: tongue. Lateral walls: cheeks. Posterior: aperture oropharyngeal isthmus’ opens into oropharynx. Border bet ween the mouth and pharynx marked by palatoglossal arch. Closure of oropharyngeal isthmus via palatoglossus ( muscles of soft palate ) to seperate oral cavity from oropharynx. The oropharyngeal isthmus lies bet ween the soft palette, and the dorsum of the tongue, and is bounded on both sides by the palatoglossal arches. Each palatoglossal arch runs downwards, laterally and for wards, from the soft palate to the side of the tongue, and consists of palatoglossus and its covering mucus membrane. The approximation of the archers shut off the mouth from the oropharynx, and is essential for deglutition. swallowing The tongue: Highly muscular organ of deglutition, taste and speech. Oral and partly pharyngeal in position. Attached by its muscles to the hyoid bone, mandible, styloid processes, soft palate and the pharyngeal wall. It has a root, an apex, a curved dorsum and an inferior surface. The dorsal mucosa is covered by numerous papillae, some of which bear taste buds. Intrinsic muscle bres are arranged in a complex interlacing pattern to allow greater mobility. It is divided by V-shaped sulcus terminalis into an anterior, oral ( presulcal ) part that faces upwards, and a posterior, pharyngeal ( postsulcal ) part that faces posteriorly. 88Eur A sucus terminalis pre succu Papillae help to increase the surface area of the tongue. All papillae have taste buds apart from liform. Types of papillae: 1. Vallate- blunt ended, largest, 8-12, V-shaped anterior to terminal sulcus. 2. Filiform- small cone shaped, mucosal projections. 3. Fungiform- round, large along margins of tongue. 4. Foliate- line folds of mucosa, sides of tongue. α Filiform fungiform Deglutition: 1. The tip of the tongue contacts the anterior part of the palate, while the bolus is pushed posteriorly in a groove bet ween the tongue and the palate. 2. The soft palate is drawn upward as a bulge forms in the upper part of the posterior pharyngeal wall and approaches the rising soft palate. 3. The tongue gradually presses more of its dorsal surface against the hard palate, the bolus is pushed posteriorly into the oropharynx. 4. The soft palate is drawn superiorly and closes off the nasopharynx. 5. Receptive space is created in the oropharynx as the root of the tongue moves slightly anterior. 6. The stylopharyngeus and upper pharyngeal constrictor muscles contract to raise the pharyngeal wall over the bolus. 7. When the bolus has reached the epiglottic vallecula, the hyoid and larynx move superior and anterior while the epiglottis is tipped inferiorly. 8. A peristaltic wave on the posterior pharyngeal wall moves inferiorly. 9. The soft palate is pulled inferiorly and approximated to the root of the tongue by contraction of muscles and pressure of the peristaltic wave. 10. The oropharyngeal cavity is closed by constriction of upper pharyngeal constrictors. 11. Relaxation of cricopharyngeus permits entry of the bolus into the oesophagus. 12. A trickle of food may enter the laryngeal aditus. 13. The peristaltic wave reaches the vallecula and presses out of the last of bolus and the cricopharyngeus remains relaxed and the bolus has largely passed into the oesophagus. 14. The peristaltic wave passes the pharynx and the epiglottis begins to turn superiorly as the hyoid bone and larynx descend. 15. Communication with the nasopharynx is re-established. 1 2 13 3 7 6 14 15 8 9 12 Oesophageal phase: Begins after relaxation of the upper oesophageal sphincter has allowed the bolus to enter the oesophagus. True peristalsis is aided by gravity and last bet ween 8 - 20 seconds. The oesophagus is a muscular tube with 3 regions: 1. Cervical- continuous with oropharynx. 2. Thoracic ( T1-T10 ). 3. Abdominal. Three normal constrictions: 1. Cervical ( C5/C6 ) due to cricoid cartilage. 2. Thoracic due to aortic arch. 3. Abdominal at oesophageal hiatus.